Problem: Khan.scratchpad.disable(); Luis sells magazine subscriptions and earns $$4$ for every new subscriber he signs up. Luis also earns a $$38$ weekly bonus regardless of how many magazine subscriptions he sells. If Luis wants to earn at least $$50$ this week, what is the minimum number of subscriptions he needs to sell?
Solution: To solve this, let's set up an expression to show how much money Luis will make. Amount earned this week $=$ $ $ Subscriptions sold $\times$ Price per subscription $+$ Weekly bonus Since Luis wants to make at least $$50$ this week, we can turn this into an inequality. Amount earned this week $\geq $50$ Subscriptions sold $\times$ Price per subscription $+$ Weekly bonus $\geq $50$ We are solving for the number of subscriptions sold, so let subscriptions sold be represented by the variable $x$ We can now plug in: $x \cdot $4 + $38 \geq $50$ $ x \cdot $4 \geq $50 - $38 $ $ x \cdot $4 \geq $12 $ $x \geq \dfrac{12}{4} = 3$ Luis must sell at least 3 subscriptions this week.